It all depends on what you prefer in terms of thickness. Major determining factors often include your budget, the climate where you live, and maybe the type of security you may require. If you live in a colder climate, then you may want to consider using a thicker glass in order to help enhance the UPVC’s ability to provide better insulation for your home, provided it is double-glazed of course. The same goes for hotter climates. The better the insulation, the cooler your home will be, so thicker glass could help with this as well.
To determine the right glass thickness, you should consult with an experienced double-glazed UPVC window provider in your area on different costs and other benefits best-suited for your home.